The invention relates to a push-pull switch with an actuating mechanism which has a handle, with an actuating tappet being connected to the handle in order to actuate a switching element and a bezel, in which the actuating tappet is mounted such that it can be displaced axially. Preferably, the actuating tappet includes a latching element which latches on the bezel during ON actuation.
A push-pull switch of the generic type has been supplied on the electrical market for years. The system used in this case operates with latches which permit two or more stop positions of the handle in the axial direction, that is to say in the direction of the switching element paths. The balls used here as latching elements move to and fro on the same path between the ON and the OFF position. The balls snap under spring load from one valley in the ON position, over a peak, into a valley located behind for the OFF position and back on the same path. In this case, the retaining force of the latching is reduced by the restoring forces of the switching elements actuated. It is therefore necessary to ensure an adequately great difference between the force actually required to snap back and the sum of the maximum restoring forces of the switching elements which occur. For the majority of fittings, the resetting force is overdimensioned, which means that the material is continuously highly stressed. Consequently, the service life is restricted and the operating comfort is reduced by the extremely hard latching.
The invention is therefore based on the object of providing a push-pull switch of the type mentioned above for electromechanical command devices which cannot be reset by the contact pressure of the switching elements actuated and offers the highest possible degree of functional reliability and operating comfort.
The object is achieved by the actuating tappet being engaged in a thread in the handle, as a result of which a pulling movement on the handle can be converted into a rotational movement of the actuating tappet in order to release the latch. This solution, according to the invention in principle, makes it possible to provide other paths for the latching elements in the ON and OFF switching operations, in order to ensure reliable latching, avoiding resetting, in the ON position. The aforementioned solution additionally offers the advantage that no additional part is required for rotational unlocking.
A particularly advantageous embodiment arises if the bezel has a recess which extends tangentially and tapers and in which, in the ON position, latching elements embodied as balls are accommodated. This embodiment permits rotational unlocking, in which the actuating tappet is rotated and, as a result, the latching elements are released gently over the contour of the recess and are moved back into their initial position, that is to say the OFF position.
In order to achieve particularly reliable latching of the balls, it is advantageous if the balls, in the ON position, are accommodated in the recess by more than half their diameter. Even severe impacts and vibration in conjunction with high restoring forces from the switching elements actuated cannot lead to resetting in the case of such an embodiment.
In addition, it is advantageous if a compression torsion spring is clamped in between the bezel and the actuating tappet, since releasing the latch may be assisted by the spring in a simple way.